1. Field of the Invention
The present invention relates to a wet mateable connection assembly for undersea applications.
In particular the present invention especially refers to a wet mateable connection assembly for electrical and/or optical cables.
In particular, the present invention especially refers to a wet mateable connection assembly for medium and high voltage electrical cables. Typically, by medium voltage cables we mean cables suitable for more than 1 kV and up to about 30 KV, and for high voltage cables we mean cables suitable for operating above about 30 kV.
2. Description of the Related Art
The oceanic/undersea energy generation is growing at a fast speed and in this field the technologies used to generate energy are dominantly “wind mills” but wave and tidal generators are showing some promising results.
The wind mills are generally built with fixed bottom structures and inter array cables are used to go from one turbine to the next.
In order to connect the wind mills or similar apparatus to an electric network, cables may be used, wherein the cable connections are “dry mate”, i.e. the ends of the cables coming from the wind mills and of the cables of the electric network or of intermediate stations are connected together (i.e. are mated, or unmated, by means of appropriate connectors) in a dry environment, to avoid the presence of water at the connector interface, which may produce partial discharges and the consequent cable faults in the presence of electrical field and subsequently laid down underwater.
Cable hubs and/or cable substations can be used for connecting two or more underwater cables of an electric network. In these cases, and especially in places where water depths exceed 40 m depth, the dry mating is more cumbersome because it implies retrieving from underwater, for example to a ship, a sunken hub or substation having a significant weight.
The dry mating is often unpractical and generally economically disadvantageous.
In offshore windmills and other submarine applications, wet mateable connection assemblies are known.
The wet mateable connection assemblies are configured to allow the cable connection to be realized directly undersea.
Known wet mateable connection assemblies utilize an insulating liquid, such as oil, and sealing arrangements between male and female connector elements to exclude seawater from the connector interfaces. As disclosed, for example, by U.S. Pat. No. 6,736,545, such connectors generally comprise a plug unit containing one or more contact probes and a receptacle unit containing an equivalent number of contacts or junctions for engagement with the contact probes, which extend into the receptacle unit when the units are connected to each other. Typically, the contacts or junctions are contained in a sealed chamber containing dielectric fluid, and the probes enter the container via one or more openings which are sealed when the units are separated.
One major problem in designing such units is the provision of seals which will adequately exclude seawater from the phase connectors even after repeated mating and unmating, and also prevent dielectric fluid from leaking out of the chamber.
WO 96/22554 relates to underwater mateable connectors suitable for high-pressure applications and provided with a connector sealing mechanism for opening and closing a passage through a connector unit.
This mechanism comprises a moveable gate body. The gate body is moveable in a lateral direction within the connector.
The connector according to WO 96/22554 is also provided with two or dual elastomer seals, and also with an intervening chamber of dielectric fluid. In each unit, the elements to be joined are enclosed in the chamber, which is a sealed fluid-filled cavity, pressure balanced to the outside environment.
U.S. Pat. No. 4,203,640 relates to an improved electrical cable coupler which incorporates a rotatable protective cover on each coupler section to protect the electrical contacts and insulation against contamination when the coupler sections are disconnected and to allow the contacts to be electrically engaged when the coupler sections are connected together. Each protective cover includes one or more openings which correspond in number and location to the electrical contacts on its coupler section. Each disc is rotatable between a protective position in which its openings are out of alignment with the respective contacts to provide protection against contamination and an operative position in which the openings are in registration with the respective contacts to expose the contacts for electrical engagement.